Area of impact: Leaves
Description: Infected areas look as though they have been dusted with white flour. Symptoms are easiest to see on leaves.
Pathogen involved: Microsphaera diffusa (a fungus)
Timing/Conditions: Occurs after pollination in cool weather.
Contributing factors: Moisture is not known to impact powdery mildew.
Management practices: Plant resistant varieties; fungicides might not be economically helpful.